Removing the limbs from the trunks of felled trees delimbing, is ordinarily an important element in the tree harvesting process. The delimbing is ordinarily accomplishes through the use of a delimbing system that includes a delimbing unit having cutting elements for severing the tree limbs extending from the tree trunk and a tree trunk loader mechanism having a mechanism for gripping and pulling the trunk of the tree to be delimbed through the delimbing unit such that the limbs extending from the trunk are severed from the trunk by a force generated between the loader mechanism and the cutting elements. Although this system works fine with equipment provided with normal horsepower ratings, this type of system can become stalled by one or more limbs that are too large for the loader mechanism to physically pull through the delimbing unit and severe from the tree trunk. What is needed, therefore, is an additional impact assembly that includes a triggering mechanism that could sense when the loader mechanism was providing a threshold limit force and which could then generate an additional severing impulse force between the delimber unit and the loader mechanism to severe the limb or limbs.